Impacts of population growth, economic development, and technical change on global food production and consumption

Throughout history, human populations have experienced deficiencies in food production. Growing populations in the past have caused local over exploitation of natural resources leading to the extinction or collapse of several ancient societies (Diamond, 2005). However, today’s resource scarcity is not only an acute problem in isolated locations; it is also a global threat. Three arguments may illustrate the global dimension of this threat. First, the total use of resources for food production over all countries has reached substantial proportions. In 2005, agriculture occupied about 38% of the global land area (FAOSTAT, 2007) yielding an average agricultural land endowment of 0.76 ha per capita.

Without technical progress and agricultural intensification and with current rates of population growth, agriculture would need an area equivalent to one half and two-third of the current terrestrial land area by 2030 and 2070, respectively, in order to maintain current food consumption levels per capita. Considering the evolution of technology, agricultural management, and food consumption preferences; the OECD-FAO Agricultural Outlook projects global increases in cropland requirements of about 9% by 2019. Existing projections of future irrigation water consumption between 1995 and 2025 (e.g., Molden, 2007; Postel, 1998; Rosegrant et al., 2002b) differ substantially and range from minus 17% to plus 228%. This variation is due to methodological and data differences as described in Sauer et al. (2010).

The second argument supporting a global dimension of food production challenges is that although some regions experience more problems than others, today’s societies are increasingly connected. Globalization has opened the door to more international trade. Thus, regional commodity supply shortage or surplus can be transferred to and mitigated by world markets. Furthermore, globalization has also influenced governmental regulations. National land use related policies are increasingly embedded in international policies. 

Since the establishment of the United Nations in 1945, many different international treaties have been adopted, which may particularly affect global food production and distribution. Environmental treaties relevant to food production include the convention on wetlands (RAMSAR convention), the Climate Change convention, and the convention on biological diversity (CBD convention). 

These treaties may limit possible expansion of agricultural land. However, expansion of cropland might be necessary to fulfill the eight Millennium Development Goals defined by the world leaders at the United Nations Millennium Summit in 2002 since they include targets for the reduction of hunger and malnutrition.

A third argument is that the cumulative impacts of local land use decisions may cause significant global environmental feedback, foremost through climate change (Alcamo et al., 2003; Foley et al., 2005; Tilman et al., 2001). There are both positive and negative agricultural impacts which influence the availability and fertility of land (Ramankutty et al., 2002), the length of the growing season (Lobell et al., 2008), fresh water endowments, pest occurrences, CO₂ fertilization, and the frequency of extreme events related to draughts, flooding, fire, and frost.

Although global commodity trade and environmental policies are important drivers for resource utilization, a variety of additional factors influence the net impact of future development on land use and food supply. These factors include technical progress, land use intensities, land quality variations, resource endowments, and food demand characteristics. Technical progress and management intensification generally reduce land scarcity. 

While improved technologies shift the production possibility frontier outwards, intensification moves production along a frontier by substituting one resource with another (Samuelson, 1948). Agricultural production can be intensified by employing more water, fertilizer, pesticides, machinery, or labor. While intensification is often measured relative to the fixed production factor land, it may also be related to output. In contrast to technical change, intensification increases at least one input requirement per unit of output. Irrigation, for example, uses per calorie less land but more water, fertilizer, and/or capital.

The variation of land quality also interacts with development. Population growth increases food demand and therefore the demand for agricultural land. Since rationally acting agents use the economically most suitable resource first, additional agricultural land is likely to be less profitable. In addition, population growth increases predominantly urban land areas (United Nations, 2004). This expansion potentially removes high quality agricultural areas since cities are usually built on fertile land (von Thünen, 1875). 

Furthermore, increased agricultural intensity due to population growth may increase land degradation over time. This could trigger a positive feedback loop where increased degradation leads to more degradation through intensification. Fourth, income growth especially in low income regions raises demand for animal based food more than demand for plant based food. Since animal food production involves an additional element in the food chain, it may in some cases increase land requirements per calorie by a factor of 10 or more relative to plant food (Gerbens-Leenes and Nonhebel, 2005). Thus, an increased demand of animal food is likely to increase total agricultural land use and management intensities with the above described implications.

To assess the complex interdependencies between population growth, economic and technological development, and the associated relative scarcities of land and water, we use the Global Biomass Optimization Model (GLOBIOM). GLOBIOM is a mathematical programming model of the global agricultural and forest sectors. Data, concept and mathematical structure of this model are described in Havlík et al. (in press) and at www.globiom.org. The core model equations are given in mathematical notation in Appendix.

 The objective function of GLOBIOM simulates the global agricultural and forest market equilibrium by maximizing economic surplus over all included regions and commodities subject to restrictions on resource endowments, technologies, and policies. The scope and resolution of regions, commodities, management options, and resources is shown in Tables 1 and 2.   Particularly, agricultural and forest product markets are represented by 28 international regions covering the entire world. The definition of regions is consistent with 11 larger regions used in energy (Messner and Strubegger, 1995) and pollution abatement models (Amann, 2004) of IIASA’s Greenhouse Gas Initiative and with the definition of more detailed regions from the POLES model (Criqui et al., 1999). Common region definitions facilitate the linkage of GLOBIOM with energy models in the context of climate and energy sustainability assessments.

 

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